Fabrication And Application Of Noble Metal Nanostructures Based On Template-plasma Etching

Noble metal nanostructures serve as a fundamental building block for nanodevices.The practicality and commercialization of nanodevices require controllable and lowcost preparation with large-area structural consistency and reproducibility.However,chemical strategies based on bottom-up methods face challenges in attaining large-area structural consistency and preparation reproducibility,while top-down strategies face challenges in achieving low-cost mass production.Thus,the development of efficient nanofabrication techniques has been a challenging problem,yet an important prerequisite for practicality and commercialization of nanodevices.This paper proposes a fusion technique that combines bottom-up and top-down approaches to enable batch production of novel nanoscale devices,such as colloidal motors and surface-enhanced Raman scattering(SERS)substrates.The proposed technique focuses on the preparation and application of precious metal nanostructures using template-plasma etching.The objective is to develop new technologies for nanoscale structure manufacturing and batch production of novel nanostructures,laying the foundation for related nanoscale devices.The proposed technique achieved several innovative results:(1)A technique for manufacturing hollow sphere structures of Pt-Ag-Au heteromultilayer nanostructures was proposed based on organic colloidal templates-based plasma etching and subsequent layer-by-layer deposition processes.The Pt-Ag-Au hetero-multilayer nanostructures exhibit hollow sphere structure with a Pt inner layer and an Au outer layer.The diameter of the hollow sphere and the size of the circular opening can be adjusted by the organic template ordered period and plasma etching parameters,while the shell thickness can be adjusted by deposition parameters.The hollow sphere structure can move directionally in a hydrogen peroxide fuel solution and exhibit chemical self-propulsion characteristics.The motion mechanism is similar to diffusive swimming,which is a new type of colloidal motor.This provides a simple way for the large-scale controllable preparation of hetero-multilayer hollow sphere motor structures and can also be used for manufacturing other nanostructure hollow spheres.(2)A batch preparation method for nanoscale semi-spherical shell structures based on template etching-angle-resolved deposition was proposed.On the basis of the organic template-assisted plasma etching technology,a series of Pt-TiO2 bilayer semispherical shells(BHNS)with different Pt distributions were constructed in a controllable manner by changing the deposition angle and order.The obtained nanoshells include the BHNSs with complete Pt outer and inner layers(or TiO2/Pt and Pt/TiO2 BHNSs)and the partially bilayered hemispherical nanoshells(PBHNSs)with incomplete Pt outer and inner layers(or TiO2/Pt and Pt/TiO2 P-BHNSs).These semispherical nano-shells are all colloidal motors that exhibit self-propelled behavior in a solution containing fuel H2O2,propelled by the Pt layer,and move in a direction parallel to the normal of the face at the center of the Pt distribution region.Typically,the TiO2/Pt(or Pt/TiO2)BHNSs move at the posture of the opening forward(or backward),exhibiting well-directional motion with a relatively low speed,while the TiO2/Pt(or Pt/TiO2)P-BHNSs move at the posture of the opening forward(or backward)with a tilted angle,showing the quasi-circular motion with a relatively high speed.Therefore,the movement of the motor can be controlled by modulating the Pt distribution.This work provides a flexible approach for preparing nano-shells with precise and adjustable Pt distributions and deepens the understanding of chemical self-propulsion behavior dependent on Pt distribution.(3)A high-sensitivity and stable silicon-gold composite hierarchical nanostructure was designed,and a mass production process for high-performance universal SERS substrates was realized based on template-based etching process.Large-area highquality template fabrication was solved by gas-liquid interface self-assembly method,and the process parameters of reactive ion etching were optimized to control the morphology of the silicon cone array.The effect of etching gas species on the morphology of the silicon cones,especially the etching parameters,was carefully studied.By changing the sputtering deposition parameters to control the final morphology of the gold nanosphere array,the optimal enhancement activity of the SERS substrate was obtained,and batch production of>1000 SERS substrates was achieved in a single process.This SERS substrate has the characteristics of clean surface,high SERS activity,good signal consistency,and strong universality.It has achieved trace detection below 10 ppb in various direct trace detection scenarios such as drugs and organic pesticides.This achievement provides a demonstration of the commercial application of universal SERS substrates.(4)A strategy for specific detection of trace heavy metal mercury based on a mixed self-assembled monolayer-modified SERS substrate was proposed.By using a trace addition method to co-modify a series of insertion molecules including electrondonating molecules(mercaptoethylamine,mercaptopropylamine)and electronwithdrawing molecules(2,3-Dimercapto-1-propanesulfonic acid,2-mercaptoethane sulfonic acid)on a universal high-performance SERS substrate surface,the capture effect of the SERS substrate on mercury was regulated.The research showed that comodification with strongly electron-donating cysteamine molecules on the SERS substrate surface can achieve specific and trace-level detection of mercury.This provides a good material basis for the development of dedicated mercury detection chips and provides a new approach for expanding the application scenarios of universal SERS substrates.